PubMed Health⌕ Search

Biomedical subjects

P de Somer

Publications and source records attributed to P de Somer.

At least 19 recordsLinked to original sources
PubMed1985

Determination of tissue-type plasminogen-activator mRNA in human and non-human cell lines by dot-blot hybridization.

A labelled cDNA clone was used in DNA-RNA hybridization on nitrocellulose filter paper (dot-blot technique) to detect and quantify mRNA for endogenous tissue plasminogen activator (PA) in cell extracts and samples of RNA purification runs. Although, for detection purposes, the assay was less sensitive than translation in Xenopus oocytes, it was at least as reliable and much more convenient for the purpose of quantitative determination. In particular, the technique was used to study the kinetics of PA mRNA formation in a human melanoma cell line (Bowes) after exposure to the tumour promoter 12-O-tetradecanoylphorbol 13-acetate (TPA). Incubation of the cells with TPA resulted in a 15-20-fold increase in cellular PA mRNA content. The effect was time- and dose-dependent: the increase in PA-specific mRNA was clearly visible as early as 4 h after initiation of TPA treatment in Bowes cells. It was blocked completely by pretreatment of the cells with actinomycin D, indicating that TPA caused enhancement of synthesis of PA mRNA rather than inhibition of PA mRNA degradation. The use of the nitrocellulose dot-blot technique also revealed that two non-human cell lines produce mRNAs which cross-react with the human PA mRNA, namely the mouse melanoma cell line B16 and the rat brain-tumour cell line, RT4-71-1. TPA was found to exert similar stimulatory effects on the synthesis of mRNAs in these cell lines as in Bowes cells.

Animals↗
PubMed1982

Messenger RNA for human tissue plasminogen activator.

A human melanoma cell line (Bowes), which secretes extrinsic (tissue-type) plasminogen activator, was used as a source for the preparation of mRNA for extrinsic plasminogen activator. The cells were lysed and total RNA was extracted with the phenol method. A poly(A)-rich RNA fraction was isolated by affinity chromatography on oligo(dT)-cellulose. This preparation was translated by oocytes into (a) protein(s) that had biological activity in the assay for extrinsic plasminogen activator. On sucrose gradient centrifugation the translatable fraction of the RNA migrated with a sedimentation coefficient of approximately 19 S, a value compatible with the molecular weight of extrinsic plasminogen activator (70 000). The translation product was characterized as being similar to or identical with authentic extrinsic plasminogen activator by the following criteria: (a) serological cross-reactivity with purified extrinsic plasminogen activator in neutralization and immunoprecipitation reactions; (b) plasminogen dependency of fibrinolytic activity and (c) apparent molecular weight of 70 000 on sodium dodecyl sulphate/polyacrylamide gel electrophoresis.

Animals↗
PubMed1981

Tissue distribution of human interferons after exogenous administration in rabbits, monkeys, and mice.

Preparations of human leukocyte (alpha) and fibroblast (beta) interferon were given intramuscularly to rabbits and monkeys, and circulating interferon was measured. In rabbits, but not in monkeys, a marked difference between the two interferons was noted in that higher titers of circulating antiviral activity were obtained with leukocyte than with fibroblast interferon. In mice, injected interperitoneally, a similar difference could be noted. However, levels of antiviral activity in homogenates of spleens and lungs did not differ between mice injected with either interferon. Fibroblast interferon that was injected intrathecally in monkeys was found to diffuse throughout the cerebrospinal canal and to reach the serum compartment. Some interferon could also be recovered from the pia mater surrounding the brain hemispheres, but none was found in the deeper layers of the brain.

Animals↗
PubMed1981

Purification of human fibroblast interferon by zinc chelate chromatography.

Human interferon was prepared by superinduction of cultures of either diploid embryonic skin and muscle cells or of the osteosarcoma cell line MG-63. The interferon so obtained was concentrated and partially purified by adsorption to controlled pore glass (CPG) beads at neutral pH and desorption by glycine-HCl buffer at pH 2. After neutralization, this interferon was applied to a column of zinc chelate which was eluted with buffers of decreasing pH. Most of the proteins eluted ahead of the interferon activity, which itself eluted in two distinct peaks. The first peak occurred in the effluent fractions around pH 5.9, and the second one in fractions around pH 5.2. The interferon found in fractions of pH 5.9 contained 5% of the original contaminating proteins. In contrast, the amount of total protein in the pH 5.2 peak was so small that it could not accurately be assayed by the fluorescamine method. Consequently, the interferon in the peak fraction was estimated to have a specific activity of about 2 x 10(9) units/mg. This material was radiolabelled and analysed by electrophoresis. A major peak of about 22000 mol. wt. with only minor contaminating proteins appeared on the autoradiographs. The total recovery of the zinc chelate chromatographical procedure was nearly 100%, and the interferon recovered from each peak behaved consistently on rechromatography. Fibroblast interferon produced by most diploid cells contained less than 10% of the variant eluting at pH 5.9. MG-63 cells and high-passage cultures of some diploid cell strains produced up to 50% of this variant.

Cells, Cultured↗
PubMed1980

Interferon induced in human leukocytes by mitogens: production, partial purification and characterization.

Interferon was induced in leukocyte suspensions from human buffy coats by exposure to phytohemagglutinin P, concanavalin A (Con A) and staphylococcal enterotoxin A, under a variety of cell culture conditions. Con A was found to rapidly (within 12 h) induce high yields of antiviral activity (1.5 units/1000 cells). Lesser yields were obtained with the other two mitogens studied. The interferon was partially purified to a spec. act. around 10(5.3) units/mg protein, by batch adsorption on controlled-pore glass (CPG) beads and desorption by ethylene glycol. This material was characterized as containing mainly gamma-type interferon. Specifically on gel filtration, a fraction of 45000 daltons was obtained which could account for virtually all antiviral activity present in the starting material. Furthermore, the ethylene glycol-eluted antiviral activity was acid-labile, serologically distinct from alpha and beta-type interferon and strictly species-specific (no activity detectable on any of the available cell species sensitive to alpha and beta-type interferon). The crude culture supernatant also contained some antiviral activity which resembled beta-type interferon in that it adsorbed to CPG, could be desorbed by pH 2 buffer, was acid-resistant and could be neutralized by a specific anti-fibroblast interferon antiserum. The CPG/ethylene glycol-purified gamma-type interefron preparation was found to inhibit the growth of certain lymphoblastoid cells (Daudi and Molt-4). It also potentiated natural killer activity of fresh donor lymphocytes. In both respects, the gamma-type interferon preparation was not significantly more active than preparations of alpha and beta-interferon of similar antiviral potency.

Chemical Phenomena↗
PubMed1979

Pharmacokinetics of E-5-(2-bromovinyl)-2'-deoxyuridine in mice.

The pharmacokinetics of the newly developed anti-herpes agent, E-5-(2-bromovinyl)-2'-deoxyuridine, was compared with that of the standard anti-herpes drug 5-iodo-2'-deoxyuridine. Both compounds were administered to mice at 100 mg/kg by either the intraperitoneal, subcutaneous, or oral route. The active blood drug levels achieved by E-5-(2-bromovinyl)-2'-deoxyuridine were considerably higher than those attained by 5-iodo-2'-deoxyuridine (serum peak concentrations: 40 to 100 and 4 to 10 mug/ml, respectively). Active blood drug levels could still be found 320 min after oral administration of E-5-(2-bromovinyl)-2'-deoxyuridine.

Animals↗
PubMed1978

Interferon inhibits C-type virus at a posttranscriptional, prerelease step.

The mode of action of interferon in JLSV 5-cells, chronically infected with Rauscher murine leukemia virus (MLV), was studied by examining the fate of preexisting labelled viral RNA in interferon-treated cells and by determining the infectivity/physical particle ratio of cell-associated and extracellular virus. Interferon added together with 3H-uridine inhibited the production of labelled virus particles even when it was only allowed to act after all viral RNA synthesis had been stopped by actinomycin D. This indicated that the interferon-induced antiviral state primarily functions at a posttranscriptional step. When interferon was given after a 3H-uridine pulse label and arrest of label incorporation by glucosamine and unlabelled uridine, it prevented a portion of the preexisting radioactive RNA from occurring in extracellular particles. However, part of the labelled viral RNA had reached a stage beyond which interferon could not prevent it from occurring in extracellular virus particles. The notion that interferon primarily affects release of fully assembled and enveloped MLV particles may be eliminated: interferon-treatment did not affect the release of particle-bound reverse transcriptase in cells treated with cycloheximide after the antiviral state had been established. It was confirmed that interferon-treated JLSV 5-cells contained an increased number of virus particles associated with the cell membrane. However, these particles were found to have a reduced infectivity compared to those associated with control cells, thus confirming the view that virions produced by interferon-treated cells are defective; perhaps lacking in certain components.

Cell Line↗
PubMed1978

Interferon treatment of NZB mice: accelerated progression of autoimmune disease.

The effect of long-term administration of interferon in New Zealand Black and New Zealand Black/New Zealand White F1 hybrid mice was studied. Treatment with moderate doses of interferon (10(4) units, five times weekly for 8 weeks) did not depress murine leukemia virus gp69/71 levels in serum and spleen, nor p30 levels in the spleen. Interferon given at 10(5.1) units (three times weekly for 37 weeks) caused an increased incidence of anti-erythrocyte antibodies in New Zealand Black mice. Finally, the hybrid mice given interferon at 10(6.0) units (three times weekly for 33 weeks) had increased renal immune complex deposits and increased incidences of proteinuria and anemia.

Anemia, Hemolytic↗
PubMed1978

In vitro cultivation of human tumor tissues. II. Morphological and virological characterization of three cell lines.

Nineteen human tumors, mostly of sarcomatous nature, were cultured in vitro. Three cell lines were isolated and further characterized: MG-57 derived from a giant cell tumor, MG-63 derived from an osteosarcoma and MG-72 derived from a xanthohistiocytoma. The cell lines varied in morphology and growth pattern. An abnormal karyotype with marker chromosomes was present in Mg-63 and MG-72. None of the cell lines spontaneously produced detectable C-type virus particles. Stimulation with IUDR and dexamethasone also failed to induce detectable particle release.

Animals↗
PubMed1977

Purification of human fibroblast interferon by zinc chelate affinity chromatography.

Zinc chelated by iminodiacetic acid linked to an insoluble matrix binds human fibroblast interferon quite selectively at neutral pH in 0.15 M NaCL. On reduction of the pH and increase of the ionic strength, the interferon is eluted. Using a pH gradient at constant high ionic strength, good purification of the interferon can be obtained, up to a final specific activity of 108.5 units/mg of protein. Approximately 60% of the applied activity can be recovered.

Cells, Cultured↗
PubMed1977

In vitro and in vivo inhibition of virus multiplicaton by microwave hyperthemia.

The effect of microwave hyperthermia (41 degrees and 43 degrees C) on virus multiplication have been explored in vitro (HSV-1 infected primary rabbit kidney cultures) and in vivo (mice infected with HSV-1 or vaccinia). In vitro the cells were inoculated with HSV-1 and heated to 41 degrees or 43 degrees C either before or after infection. Virus yields were significantly decreased when the cells were exposed to hyperthemia within the first few hours after infection, while hyperthemia was without effect when applied before infection or with several hours delay after infection. In mice inoculated intranasally with HSV-1, mortality due to herpes encephalitis was significantly reduced upon daily exposure to microwave hyperthermia from the day of infection onward. In mice inoculated intravenously with vaccinia, a significant decrease in the number of specific tail lesions was observed if the animals were exposed to microwave hyperthermia within the first three days after infection, while irradiation prior to infection or delayed until several days after infection did not exhibit an appreciable effect. Our data suggest that microwave hyperthermia interferes directly with the virus multiplication cycle both in vitro and in vivo.

Animals↗
PubMed1977

Analysis of murine C-type virus structural proteins by rocket and crossed immunoelectrophoresis.

We have examined the structural proteins of Rauscher murine leukemia virus (R-MuLV) by means of rocket immunoelectrophoresis and crossed immunoelectrophoresis, using polyspecific antisera to Tween/ether-disrupted purified R-MuLV. Fifteen different precipitation lines were recognized in virus lysates. Using five reference antisera prepared to purified R-MuLV-structural proteins, the precipitation lines of p 10, p 15, p 30 and gp 69/70 were identified. These techniques, although less sensitive than radioimmunoassay, have several advantages, such as simplicity, direct control of precipitation reactions and possibility of using crude antigen preparations.

Animals↗